UPSC 2023 Prelims Analysis, UPSC Prelims Question Paper With Answer Key 2023

1 .

Consider the following countries :

1. Bulgaria
2. Czech Republic
3. Hungary
4. Latvia
5. Lithuania
6. Romania

How many of the above-mentioned countries share a land border with Ukraine?

A)

Only two

B)

Only three

C)

Only four

D)

Only five

Correct Answer : Option (A) - Only two

Note : As per the map given below, only Hungary and Romania share their land borders with Ukraine.

Category : General Studies

2 .

With reference to the Earth's atmosphere, which one of the following statements is correct?

A)

The total amount of insolation received at the equator is roughly about 10 times of that received at the poles.

B)

Infrared rays constitute roughly two-thirds of insolation.

C)

Infrared waves are largely absorbed by water vapour that is concentrated in the lower atmosphere.

D)

Infrared waves are a part of visible spectrum of electromagnetic waves of solar radiation.

Correct Answer : Infrared waves are largely absorbed by water vapour that is concentrated in the lower atmosphere.

Note : * The earth’s surface receives most of its energy in short wavelengths. The energy received by the earth is known as incoming solar radiation which in short is termed as insolation.

* The atmosphere is largely transparent to shortwave solar radiation. The incoming solar radiation passes through the atmosphere before striking the earth’s surface. Within the troposphere water vapour, ozone and other gases absorb much of the near infrared radiation.

Hence, statement (c) is correct.

Source : Ncert

Category : General Studies

3 .

Consider the following statements :

Statement-I : The soil in tropical rain forests is rich in nutrients.
Statement-II : The high temperature and moisture of tropical rain forests cause dead organic matter in the soil to decompose quickly.

Which one of the following is correct in respect of the above statements?

A)

Both Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I

B)

Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I

C)

Statement-I is correct but Statement-II is incorrect

D)

Statement-I is incorrect but Statement-II is correct

Correct Answer : Option (D) - Statement-I is incorrect but Statement-II is correct

Note : * Contrary to the belief that all that vegetation, warmth, and moisture that the soil must be very rich, the soil in tropical rainforests is very poor. Hence, statement 1 is not correct.

* The high temperature and moisture of tropical rainforests cause dead organic matter in the soil to decompose more quickly than in other climates, thus releasing and losing its nutrients rapidly.

* The high volume of rain in tropical rainforests washes nutrients out of the soil more quickly than in other climates. Hence, statement 2 is correct.

* If the soil is so poor in tropical rainforests, how does such a dense array of shrubs and trees grow there? - On the ground of the rainforest, there is a thick layer of quickly decaying plants and animals. Nutrients are washed by the heavy rains almost directly from the rotting surface material into the trees without entering the soil much.

Source : Wtamu

Category : General Studies

4 .

Consider the following statements :

Statement-I : The temperature contrast between continents and oceans is greater during summer than in winter.
Statement-II : The specific heat of water is more than that of land surface.

Which one of the following is correct in respect of the above statements?

A)

Both Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I

B)

Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I

C)

Statement-I is correct but Statement-II is incorrect

D)

Statement-I is incorrect but Statement-II is correct

Correct Answer : Option (D) - Statement-I is incorrect but Statement-II is correct

Note : * The specific heat is the property of a substance which determines the change in the temperature of the substance (undergoing no phase change) when a given quantity of heat is absorbed (or rejected) by it.
* The temperature contrast between continents and oceans is greater during summer than in winter because land heats up faster than water. Hence, statement-I is correct.

* Land and water heat up and cool down at different rates, known as their "specific heat". In the summer, land heats up faster and to a higher temperature than water, resulting in a greater temperature difference.

* For places with relatively well-defined seasons like India and Northern Europe, this will mean a large difference in water and land temperatures especially during the late spring/early summer and late autumn/early winter. Hence, statement II is correct.

Source : ncert

Category : General Studies

5 .

Consider the following statements:

* In a seismograph, P waves are recorded earlier than S waves.
* In P waves, the individual particles vibrate to and fro in the direction of wave propagation whereas in S waves, the particles vibrate up and down at right angles to the direction of wave propagation.

Which of the statements given above is/are correct?

A)

1 only

B)

2 only

C)

Both 1 and 2

D)

Neither 1 nor 2

Correct Answer : Option (C) - Both 1 and 2

Note : * When an earthquake occurs, two main types of vibratory waves move through the body of the earth from the point of fracture. The primary, or P, waves travel most quickly and are the first to be registered by the seismograph. Secondary, or S, waves travel more slowly. Hence, statement 1 is correct.

* As S waves have a greater amplitude than P waves the two groups are easily distinguishable on the seismogram.

* Seismic P waves are also called compressional or longitudinal waves, they compress and expand (oscillate) the ground back and forth (to and fro) in the direction of travel, like sound waves.

* Particle motion is parallel to the direction of propagation (longitudinal). Material returns to its original shape after the wave passes.

* The S waves in an earthquake are examples of Transverse waves.

* In a transverse wave the particle displacement is perpendicular to the direction of wave propagation. The particles do not move along with the wave; they simply oscillate up and down about their individual equilibrium positions as the wave passes by. Pick a single particle and watch its motion. Hence, statement 2 is correct.

Category : General Studies

6 .

With reference to coal-based thermal power plants in India, consider the following statements :

1. None of them uses seawater.
2. None of them is set up in water-stressed district.
3. None of them is privately owned.

How many of the above statements are correct?

A)

Only one

B)

Only two

C)

All three

D)

None

Correct Answer : Option (D) - None

Note :

* According to above given figures it is clear that coal based thermal power plants in India use seawater. Hence statement 1 is not correct.

Hence, statement 2 is correct.

* Adani Power Limited is the largest private thermal power producer in India with an installed capacity of 13,650 MW. hence, statement 3 is not correct.

Category : General Studies

7 .

'Wolbachia method' is sometimes talked about with reference to which one of the following?

A)

Controlling the viral diseases spread by mosquitoes

B)

Converting crop residues into packing material

C)

Producing biodegradable plastics

D)

Producing biochar from thermo-chemical conversion of biomass

Correct Answer : Controlling the viral diseases spread by mosquitoes

Note : Wolbachia are natural bacteria present in up to 60% of insect species, including some mosquitoes. Wolbachia bacteria cannot make people or animals (for example, fish, birds, pets) sick.

* For many years, scientists have been studying Wolbachia, looking for ways to use it to potentially control the mosquitoes that transmit human viruses.

The World Mosquito Program’s Wolbachia Method :

* The WMP's field teams release male and female Aedes aegypti mosquitoes with Wolbachia over a number of weeks. These mosquitoes then breed with the wild mosquito population. Over time, the percentage of mosquitoes carrying Wolbachia grows until it remains high without the need for further releases. Mosquitoes with Wolbachia have a reduced ability to transmit viruses to people, decreasing the risk of Zika, dengue, chikungunya and yellow fever outbreaks.

Hence, option (a) is correct.

Category : General Studies

8 .

Consider the following activities :

1. Spreading finely ground basalt rock on farmlands extensively
2. Increasing the alkalinity of oceans by adding lime
3. Capturing carbon dioxide released by various industries and pumping it into abandoned subterranean mines in the form of carbonated waters

How many of the above activities are often considered and discussed for carbon capture and sequestration?

A)

Only one

B)

Only two

C)

All three

D)

None

Correct Answer : Option (C) - All three

Note : * Carbon sequestration is both a natural and artificial process by which carbon dioxide is removed from the Earth’s atmosphere and then stored in liquid or solid form.
* Ground basalt has been used as mineral fertiliser since the early thirties. Ground basalt captures CO2 from the atmosphere and the soil pore space, raises the soil pH and reduces ocean acidification. One tonne of basalt captures 0.153–0.165 tonne CO2, depending on infiltration rate.

* Ground basalt added to agricultural fertiliser captures atmospheric carbon dioxide (CO2), raises the soil pH, reduces ocean acidification and supplies important nutrients such as magnesium, potassium, calcium, iron and phosphorus. Hence, 1 is correct.

* Oceans absorb about 25% of the carbon dioxide emitted through human activities each year.

* As such, the polar regions absorb more carbon dioxide and by 2100, most of the global oceans are expected to be made up of carbon dioxide, potentially altering the chemistry of the ocean, making it more acidic.

* Since carbon makes ocean acidic, increasing alkalinity of oceans would help in carbon sequestration. Hence, 2 is correct.

* In carbon capture and storage (CCS) processes, carbon dioxide is first separated from other gases contained in industrial emissions.

* It is then compressed and transported to a location that is isolated from the atmosphere for long-term storage.

* Suitable storage locations might include geologic formations such as deep saline formations (sedimentary rocks whose pore spaces are saturated with water containing high concentrations of dissolved salts), depleted oil and gas reservoirs, or the deep ocean. Hence, 3 is correct.

Category : General Studies

9 .

'Aerial metagenomics' best refers to which one of the following situations?

A)

Collecting DNA samples from air in a habitat at one go

B)

Understanding the genetic makeup of avian species of a habitat

C)

Using air-bome devices to collect blood samples from moving animals

D)

Sending drones to inaccessible areas to collect plant and animal samples from land surfaces and water bodies

Correct Answer : Collecting DNA samples from air in a habitat at one go

Note : * Metagenomics is the study of the structure and function of entire nucleotide sequences isolated and analysed from all the organisms (typically microbes) in a bulk sample.

* Metagenomics is often used to study a specific community of microorganisms, such as those residing on human skin, in the soil or in a water sample.

* Aerial metagenomics is a scientific field that involves studying the genetic material present in the air, specifically the DNA and RNA of microorganisms suspended in the atmosphere.

* It focuses on the analysis of the microbial communities or microbiomes found in the air samples collected from various environments such as outdoor air, indoor air, and airborne particles.

Hence, option A is correct.

Category : General Studies

10 .

'Microsatellite DNA' is used in the case of which one of the following?

A)

Studying the evolutionary relationships among various species of fauna

B)

Stimulating �stem cells� to transform into diverse functional tissues

C)

Promoting clonal propagation of horticultural plants

D)

Assessing the efficacy of drugs by conducting series of drug trials in a population

Correct Answer : Studying the evolutionary relationships among various species of fauna

Note : Microsatellite DNA, also known as short tandem repeats (STRs), is one of the best suitable genetic markers for analyzing pedigree, population structure, genome variation, evolutionary process, and fingerprinting purposes. Hence, option a is correct.

Category : General Studies

UPSC 2023 (Prelims) Questions (Set B)